Digging adjustment mechanism for wheel-type trenching machine



Sept. 11, 1956 F. w. WELLS DIGGING ADJUS TMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE 7 SheetS -Sheet 1 Filed March 29, 1950 Sept. 11, 1956 F. w. WELLS 2,762,137

DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE Zhwentor pt 1956 F. w. WELLS 2,762,137

DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE Filed March 29, 1950 7 Sheets-Sheet 3 Isnventor Wh/LZZL Sept. 11, 1956 F w WELLS Filed March 29, 1950 2,762,137 DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE 7 Sheets-Sheet 4 8 56 39 \Z// Y I g Inventor p 1956 F. w. WELLS 2,762,137

DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE Filed March 29, 1950 7 Sheets-Sheet 5 W 3nnentor p 1956 F. w. WELLS 2,762,137

DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE Filed March 29, 1950 7 Sheets-Sheet 6 Sept. 11, 1956 F. W. WELLS 2,762,137

DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHING MACHINE 7 Sheets-Sheet 7 Filed March 29, 1950 United States Patent DIGGING ADJUSTMENT MECHANISM FOR WHEEL-TYPE TRENCHENG MACHINE Frank W. Wells, Pasadena, Calif. Application March 29, 1950, Serial No. 152,611

Claims. (Cl. 37 97 The invention relates to certain novel and advantageous functional and structural improvements in the field of grading and loading and ditch-digging equipment.

Ditch-diggers up to this time have conventionally been mounted upon tracks which are ordinarily steered by locking one track and driving with the other track. These ditch-diggers have no high-speed transport provision, because their weight and the basic track design does not permit movement except at very slow speeds. Because of the cleats, the tracks, and the locking of the tracks for steering, these machines cause damage to lawns, sidewalks, and curbs, and in many places are restrained by law from running on public roads. They ordinarily are transported by carrying on a separate vehicle, with additional capital expense and lost time during the loading and unloading periods which are necessary even for movement of very short distances. They conventionally are single purpose machines, being capable of digging trenches alone, and other means must be provided for grading ahead of the ditch and for backfilling the ditch after it is dug and for loading surplus dirt into means for conveying it away. Therefore, they are uneconomical on certain classes of ditch-digging work, because of the cost of their operation while digg ng, the damage they do to sod, sidewalks, curbs, etc., the lost time in putting them into operation and the necessity for expensive additional equipment; and, of course, Where grading must be done ahead of the ditching operation, duplicate time must be spent because the operations cannot be combined as they can in the invention to be described.

Therefore, a major aim of the invention is to provide maneuverability and mobility which is accomplished by the instaliaticn of a trench digging machine upon a rubber-tired power unit. Another of the main objects of the invention is the provision upon this rubber-tired power unit of a digging unit so designed to eliminate the vibration and bounce which would be characteristic of the operation of a ditch-digging machine upon rubbertired vehicles. This has been done by the development of a wheel-type digging machine, which has the important operating advantage of distributing the digging pressure against a curved surface rather than a vertical or angular surface created by a ladder type ditch-digging machine.

Another very important object of the invention is to make it possible to grade a path ahead of the ditch-digging wheel simultaneously with the ditch-digging operation. This is accomplished by combining on the same power unit a front-mounted grading or bulldozing tool.

A further important object of the invention which is attained in this manner is to obtain counter-balancing forces with the front-mounted tool to compensate for the weight of the ditch-digging rear-mounted tool, in order to make it possible to provide a more maneuverable unit through the resulting shorter wheel base required and a more economical overall unit because the counter-balancing effect is acquired with a tool adding value to the machine rather than by the substitution of ballast weight.

Fatented Sept. 11, 1956 It has heretofore been customary to suspend a trench digging attachment by means of cables from a superstructure provided on the tractor. These cables fail to otter positive guidance of the trencher while it is operating so as to maintain the ditch formed thereby in vertical alignment with the tractor. Furthermore the use of cables for suspending the trenching attachment and for lowering and elevating this requires the provision of special winches and drive mechanism which are relatively expensive.

It is a yet further object of this invention to provide a novel trench-digging attachment and means for mounting the same on an automotive tractor which provides positive guidance for the trench-digging attachment in all positions through which it travels so as to assure proper vertical alignment of the ditch dug thereby.

The manner of accomplishing the foregoing objects as well as further objects and advantages will be made manifest in the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevational view of a preferred embodiment of the invention with the rotary trenching wheel thereof and the forward counter-balancing grader shown in elevated position in full lines as when the tractor of the invention is traveling on a highway, said trenchingwheel and grader being shown in broken lines positioned as when simultaneously grading a strip of ground and digging a trench therein.

Fig. 2 is a fragmentary side elevational view of a loading tool comprising an optional form which the counterbalance of the invention may take.

Fig. 3 is an enlarged rear elevational view of the invention with the discharge conveyor shown in full lines as when discharging dirt to the left and in broken lines as when discharging dirt to the right.

Fig. 4 is a diagrammaticv perspective view of the transmission of the invention.

Fig. 5 is an enlarged vertical sectional view taken on the line 55 of Fig. 4.

Fig. 6 is an enlarged vertical sectional view taken on the line 66 of Fig. 4.

Fig. 7 is a diagrammatic enlarged fragmentary sectional View taken on the line 77 of Fig. 3.

Fig. 8 is a perspective view of the mast and channel guides of the invention with certain parts shown in disassembled relation therewith.

Fig. 9 is an expanded perspective viewof the trenchwheel frame of the invention.

Fig. 10 is a perspective view of a roller supporting yoke which extends forwardly from said trenching-wheel frame and by which the trenching-wheel is guided and lowered or lifted.

Fig. 11 is an expanded perspective view of the parts comprising the hydraulic jack of the invention by which the trenching wheel is lowered or lifted.

Fig. 12 is a perspective view of the cross-head which slides vertically within the toast of the invention, and the elevation of which is accomplished by said jack to control the lowering and lifting of the trenching-wheel.

Fig. 13 is a perspective view of the loose dirt discharge conveyor of the invention.

Fig. 14 is an enlarged horizontal sectional view taken on the line 1414 of Fig. 3 and illustrates the reverse gear transmission through which the loose dirt conveyor is driven.

Fig. 15 is a perspective view of a digging bucket of the trenching-wheel of the invention.

Fig. 16 is a disassembled view of the trenching-wheel of the invention with the dirt guides associated with said wheel shown spaced axially therefrom.

Referring specifically to the drawings, the preferred embodiment of the invention shown in Fig. 1 comprises a combination grader and trencher which includes a short-wheel-base, four-wheeled, rubber-tired tractor 21, a trenching attachment 22 and a counter-balancing-grading device 23.

The tractor 21 can be a modified standard or special industrial tractor including a power unit 24 on which a pair of rear drive wheels 25 and a dirigible pair of front wheels 26 are mounted. The power unit 24 includes a motor 27, a transmission 28 (Fig. 4) and a rear-axle-and differential assembly 29, (Fig. 3) all of which are united together as a single structural unit.

The motor 24 has a structural cross member 30 on which the dirigible front wheels 26 are mounted, and the drive wheels 25 are mounted on the usual drive axles (not shown) which journal in bearings provided in the rear axle and differential assembly 29 (Fig. 3). The motor 27 also has a drive connection with an oil pump for actuating a hydraulic control system 36 which will be described in detail hereinafter.

Provided at the rear end of the motor 27 are the usual flywheel and clutch (not shown) which are enclosed within a housing 37 (Fig. 4) embodied with said motor.

The principal modification of the tractor 21 above referred to consists in producing the transmission 28. This is effected by separating the original transmission 38 from the clutch housing 37, to which it is normally attached, and interposing between said clutch housing and the transmission 38 a secondary transmission 39 which is united at its opposite ends to said housing 37 and to the transmission 38 to form a unitary assembly which comprises the transmission 28 of the invention.

Also united with the secondary transmission 39 is a reversible power takeoff 40 through which power from the motor 27 is transmitted to the rotary trenching-wheel 22.

The original transmission 38 retains a shaft 41 which was originally driven by a connection between this shaft and the engine clutch in the housing 37. It also retains the gear trains and control means by which shaft 41 is connected with a drive-shaft 42 leading to the rear wheels 25. These gear trains (not shown) provide for four speeds forward and one speed in reverse.

The secondary transmission 39 provides a means for making a direct connection between the engine 27 and the shaft 41 of transmission 38. It also includes means for introducing various gear trains between the engine 27 and shaft 41 so as to modify the speed ratios optionally provided by original transmission 38 and with which the rear wheels 25 are driven from the engine.

Fig. 6 clearly illustrates transmission 39 as including a shaft 43 which connects at its front end with the engine clutch, and the rear end of which is in coaxial alignment with and abuts against the shaft 41. Close to their abutting ends, the shafts 41 and 43 are provided with splines 44 and 45. Fitting over the Spline 44 is a sleeve which is internally splined to fit the spline 44 and externally splined to fit a double gear 51 having external teeth 52 and 53 on opposite sides of an external groove 54, the two sets of teeth 52 and 53 being of different pitch radius. A yoke 55 slidably mounted on a cover plate 56 of a housing 57 of the secondary transmission 39 extends into the groove 54 and is actuated by a manual control lever 58 (Fig. 4) to shift the double gear 51 axially on the spline sleeve 50.

The sleeve 50 is secured in place on the shaft 41 by a screw 59 to prevent endwise movement of said sleeve.

Slidably fitting the spline 45 is an internally splined sleeve 60. Provided externally on sleeve 60 at opposite ends thereof are pinion gears and 66. The teeth of the gear 65 corresponds to those of the external spline on sleeve 50 so that double gear 51 is adapted to be slid along said sleeve until it receives the teeth of gear 65 whereupon gear 51 functions as a coupling, locking shafts 43 and 41 and forming a direct drive connection between the motor 27 and original transmission 38.

The sleeve 60 is held in end to end engagement with the sleeve 50 by a split spring ring 67 which snaps into into an annular recess provided therefor in the spline 45.

The housing 57 for secondary transmission 39 includes a bearing 69 in which shaft 43 journals and a bearing 70 in which shaft 41 journals. This housing also provides mountings for stationary jack shafts 71 and 72. R0- tatable on the jack shaft 71 is a double gear 73 having a pinion gear 74, spring detents 75, and a plate gear 76 which is recessed and held against the detents by a ring 77 trapped in a suitable annular recess provided in the gear 73 at the base of the pinion 74. The gear 76 is in constant mesh with pinion gear 66 and is constantly driven thereby. Also mounted on jack shaft 71 is multiple gear 80 having gears 81, 82 and 83 formed thereon. Gear 82 is formed to mesh with gear 52 when the latter is placed in radial alignment therewith and gear 83 is formed to mesh with gear 53 when the latter is radially aligned therewith.

Provided on shaft 72 is a gear 84 which meshes with pinion 74 and has a pinion 85 which meshes with gear 81. It is thus seen that by manipulation of lever 58 (Fig. 4) the option is provided to operator, through control of the secondary transmission 39, of either locking shaft 43 to shaft 41 for direct drive and cutting out the secondary transmission 39, or, by shifting the gear 51 to mesh either gear 52 with gear 82, or gear 53 with gear 83, to provide forward speeds with rear wheels 25 travelling at creeping rates which can be further modified by interposing between the shaft 41 and the shaft 42 one or another of the gear trains available in the original gear transmission 38.

The shaft 43' has fixed thereon a miter gear 86 from which the power takeoff 40 (Fig. 5) is driven. This takeoff includes a housing 87 mounted on one side of the secondary transmission 39 and provides bearings 88 and 89 in which a shaft 90 journals and bearings and 96 in which a shaft 97 journals. Mounted in the housing 87 in an intermediate position between and parallel with the shafts 90 and 97 is a stationary shaft 98. Fixed on one end of shaft 90 is a miter gear 99 which meshes with gear 86. The shaft 90 has a spline 100 with which a double gear 101 is slidably meshed, said gear having a yoke groove 102 and gears 103 and 104 of diiferent diameters. Shaft 97 has fixed thereto a gear and a sprocket 111, the latter being outside the housing 87.,

Rotatably mounted on shaft 98 is a triple gear 112 having formed integral therewith a pinion 113 which constantly meshes with gear 110, and gears 114 and 115 of difierent diameters and which are adapted to be brought respectively into mesh with gears 103 or 104 by the application of a yoke (not shown) which fits into the yoke groove 102 and which is operable by lever 116 to shift gear 101 axially (Fig. 4).

It is thus clear that rotation of shaft 43 is always trans-- mitted through gears 86 and 99 to shaft 90, and that by actuation of lever 116 the operator of the grader and trencher 20 may optionally cause the sprocket 111 to be rotated at either of two speeds (depending upon which of the gears 103 or 104 is placed in mesh with the gear 112) or, by placing the gear 101 as shown in Fig. 5, the drive between the shaft 43 and the sprocket 111 may be disconnected.

The tractor 21 is provided with the usual steering wheel 117 (Fig. 1) for steering the front wheels 26. A seat 118 is also provided for the accommodation of the operator. The original transmission 38 (Fig. 4) is provided with a gear shift lever 119 (Figs. 1 and 4) which can readily be reached by the operator sitting in the seat 118 for control of said transmission,

The trenching attachment 22 and grader 23 not only cooperate functionally and simultaneously in the op eration of the device 20 but they have a common main frame 120 (Figs. 1 and 2) including longitudinal channels 121 which are connected by suitable cross-bars near their front and rear ends and are also united near their front ends to cross-member and, near their rear ends, to the rear axle assembly 29 of the tractor power unit 27. Extending upwardly from the frame is a rigid grader guide frame including vertical side members 126. Extending upward centrally from channels 121 are standards 127 upper ends of which are connected forwardly to the main frame 120 by braces 128. Provided on the channels 121 and extending downwardly therefrom are short legs 129 which constitute mounts for pivot pins 130.

Pivotally swung on pivots 131 in upper ends of standard 127 are spaced side-arms 132 of the counter-balancing and grading attachment 23 of the invention. These arms 132 are connected by pivots 133 at their forward ends with a mold board 134 adapted for grading operations when arms 132 are lowered to bring the mold board 134 in contact with the ground.

Mold board 134 and arms 132 are also of sufiicient weight to form a forwardly disposed counterbalance for the trenching attachment 22 as will be made clear hereinafter.

The arms 132 are suitably spaced by a spacing angle member 135. Provided on opposite sides of the device 20 with their lower ends mounted on the pivots are jacks 140, plungers 141 of which are connected at their upper ends by pivots 142 to arms 132.

The main frame 120 also includes a trenching attachment mast 143 (Figs. 1 and 3) which preferably consists of two channel members 144 the lower ends of which are rigidly fixed to the side frame members 121 and the upper ends of which are connected together by a cross-channel 145. The mast 143 is preferably vertically disposed and is braced by structural members 14-6 which extend forwardly from the upper end of the mast to the upper ends of standards 127 to which said members connect. The lower ends of the mast channels 144 are connected together by a cross-channel 147.

Lying in the same longitudinal vertical planes with the channel members 144 are arcuate channel guides 148 the upper end portions of which are curved about a relatively short radius and are Welded to the channels 144. The balance of each of the curved channel guides 148 is curved about a much greater radius and the lower ends of said guides are rigidly fixed to the rear ends of the main frame side members 121.

Also provided on the main frame 120 are short standards 149 on the upper ends of which bearing tubes 150 and 151 are mounted on a common horizontal transverse axis 152 (Fig. 7). Journalled in ball bearings 156 provided in the tube 150 is a shaft 157 carrying a sprocket 158 which is radially aligned and connected to sprocket 111 by an endless'chain 159. Mounted on the other end of shaft 157 is a sprocket 160 the purpose of which will be made clear hereinafter.

The trenching attachment 22 includes a trenching wheel frame 161 (Figs. 1, 3, 7 and 9) on which a trenching wheel 162 is rotatably mounted. The trenching wheel frame 161 includes cross-members 163 and 164 (Fig. 9)

which are connected by inverted U-shaped members 165 and atriangular sub-frame which carries two pairs of guide rollers 171 and 172 (Fig. 1). Secured to the frame members 165 and extending forwardly therefrom is aryoke 173 (Fig. 1), including side bars 174 (Figs. 1, 3 and 10) which are connected by shafts 175 and 176. Rotatably mounted on outer ends of shaft 176 are guide rollers 177 which extend into and are guided by channel guides 148.

The trenching attachment 22 is provided with a drive shaft 178 (Fig. 7) having bearings 179 mounted in hearing housings 180 the latter fitting into half round notches 181 provided in endplates 182 of the trenching wheel frame cross member 164 (Fig. 9), so that the shaft 178and associated elements may be readily changed in order to substitute for one trenching wheel162, another trenching wheel differing in width from the first. The bearing housings 180 include sleeves 183 on which hubs 184, provided at rear ends of a pair of arms 185, are pivotally mounted. The forward ends of arms 185 have hubs which are pivotally mounted on outer ends of bearing tubes 150' and 151 provided at the upper ends of frame standards 149.

The arms 185 are thus free to swing vertically about the axis 152 and lie close to and just outwardly from the mast channel members 144 and the channel guides 148 (Fig. 7). The frame 161 is also freely rotatable relative to the arms 185, about the axis of shaft 178, the arms 185, however, maintaining the axis of shaft 178 at a fixed distance from the axis 152 of the shaft 157 and sprocket 160 mounted thereon. The sprocket 160 is connected to an endless chain 191 to a sprocket 192 fixed on the corresponding end of shaft 178 so that power may at all times be transmitted to the shaft 178 from the power takeoff 40 through the chain 191.

Fixed on the shaft 178 are trench wheel driving gears 193 having substantial hubs 194.

The trenching wheel 162 (Figs. 1, 3, 7 and 16) comprises a pair of spaced annuli 195 which are united in coaxial spaced relation by an endless series of digging buckets 196 extending outwardly therefrom. Each of said annuli is provided with an endless series of axially disposed gear teeth 197. The trenching wheel 162 is supported on and held in correct position by the gears 193 and guide rollers 171 and 172. When the trenching wheel is thus supported, the gear teeth 197 mesh with the teeth of the gears 193' so that rotation of the shaft 178 rotates the trenching wheel 172 about its own axis.

The digging buckets 196 may be of any conventional design, the dirt picked up thereby in the operation of the invention being confined in said buckets, as these rise with the rotation of wheel 162, by an arcuate guide plate 198.

As the buckets rise towards the upper end of the guide plate 198 the dirt carried thereby is discharged downwardly over a delivery plate 199 onto a loose dirt conveyor 200 (Figs. 3 and 13). From this point, buckets 196 continue past a short arcuate guide plate 205 and an arcuate grill guide 206 (Fig. 16) which permits dirt to gravitate into the buckets but screens out boulders which are too large to properly enter the buckets from the inside of the wheel. The arcuate guides 198, 205 and 206 and the delivery plate 199 are rigidly secured in place within the trenching wheel 162 by being suitably secured to the trenching wheel frame 161.

Secured on the right hand frame 165 (Fig. 9) is a bracket 207 on which is mounted a reversible conveyor drive gear-box 208 (Fig. 14).

Iournalling in bearings 209 provided in said gear box is a shaft 210 the latter having a sprocket 211 fixed on its outer end and a miter gear 212 fixed on its inner end. The sprocket 211 is in radial alignment with a sprocket 213 provided on the adjacent end of shaft 178 and is connected thereto by an endless chain 214 (Fig. 3). Extending through and journalled in the gear-box 208, in the same plane as the shaft 210 and at right angles thereto, is a splined shaft 215 on which is slidably mounted an internally splined sleeve 216 on which are fixed miter gears 217 and 218. The sleeve 216 has a shifting groove 219 into which extends a pin 220, the latter being mounted eccentrically on a gear box control shaft 221. The shaft 221 has a manual control crank 222 which is provided with a detent mechanism 223 which holds the crank 222 in either of two positions 180 apart and which either causes the gear 217 or the gear 218, as the case may be, to be in mesh with the gear 212, thereby giving the operator the option of connecting the shaft 210 to the shaft 215 for driving the latter in either direction. Fixed on a rearwardly extending end of shaft 215 is a sprocket 228.

The function of the gear-box 208 is to provide a controllable drive for loose dirt conveyor 200, whereby this conveyor may be driven in either direction thereby determining the side of the device 20 at which loose dirt, delivered onto the conveyor 200 from the trenching wheel 162, is discharged from the conveyor.

The conveyor 200, as shown in Figs. 3 and 13, is of a conventional arcuate form and is mounted on the trenching attachment frame 161 so as to extend through the open spaces in the inverted U-shaped frame members 165 and rest on the triangular frame 170. The conveyor 200 includes an arcuate frame 229 at opposite ends of which conveyor belt pulleys 230 and 231 are pivotally'mounted, the latter pulley having a drive shaft 232 on which is fixed a drive-sprocket 233.

The sprocket 233 is fixed on the forward end of shaft 232 and is connected by an endless chain 234 to the sprocket 228 of the reversing gear-box 208.

Provided 'on the right frame 165 is a bracket 235 having a pin 236 (Fig.9) at its extremity which is coaxial with sprocket 228 and pivotally carries an arm 237 having a bearing 238 at its lower end in which the adjacent end of shaft 232 journals (Fig. 3). Thus the conveyor 200 is seen to be supported at its forward edge by the arcuate frame 229 resting on the fixed triangular frame 170. Along its rear edge at its right end it is supported by the arm 237 (Fig. 3) so as to permit conveyor '200 to be optionally shifted between its full line position, in which it is shown in Fig. 3,'to the broken line position in which it is shown therein. To aid in supporting the conveyor 200 and facilitate its being shifted transversely at the option of the operator, the conveyor 200 is provided along its rear edge with an arcuate rack 239 (Fig. 3) which rides on a gear 240 (Fig. 9), the latter being fixed on the forward end of a short shaft 245 having a handle 246 secured to the rear end of said shaft by a pin 247.

The shaft 245 journals in a suitable aperture provided in a lug 248 extending laterally from the frame member 163 (Fig. 9).

Referring now to Figs. 1, 3 and 12, the device 20 includes a hydraulic jack 249 which is mounted in the plane of the mast channel members 144, midway therebetween, the lower end of said jack being supported on frame cross-member 147, said jack being closed at its lower end and having a plunger 250 extending from the upper end thereof. The upper end of plunger 250 connects with a cross-head 251 (Figs. 3 and 12) having an inverted U-shape and carrying sheaves 252. Vertically spaced stub shafts 253 extend laterally from opposite edges of cross-head 251, these carrying rollers 254 which lie within the inwardly facing channels 144 and are guided thereby as the cross-head 251 is raised or lowered along the mast 143 by the passage of liquid into or from the lower end of jack 249. One end of each of two cable 255 is secured to shaft 175 (Fig. 3) and after extending upwardly and over sheaves 252, these cables extend downwardly and are secured fast to the main frame 120 adjacent the lower end of the mast 143.

The hydraulic control system 36 previously mentioned will now be described in detail. This system includes an oil reservoir 26f) (Fig. 1) from which oil is delivered through a pipe 261 to the pump 35 which is continually driven by the motor 27 when the'latter is running. Oil' is delivered from the pump 35 through line 262 to a central valve 263 and then directed thence by the actuation of control levers 264 and 265. Oil lines 266 lead from the valve 263 to the lower end of hydraulic jacks 140. The valve 263 is connected by an oil line 267 to a bleeder valve 268 and the latter is connected by a line 269 with lower end of hydraulic jack 249. A stream of oil is continually being withdrawn from the reservoir 260 through the line 261 by the pump 35 and discharged therefrom under high pressure through the line 262 and into the valve 263. .When the valve control levers 264 and 265 are both in neutral position this oil returns from the valve 263 through a bypass line 270 to the reservoir 260. When the control lever 264 is moved to close the line 274 and divert the oil from line 262 to lines 266 i this causes this oil to extend the'plungers 141 of jacks 149 and lift the arms 132 and the mold board 134 supported thereon to an elevated position as shown in full lines in Fig. 1. In a similar manner by manipulation of control lever 265 the hydraulic jack 249 is actuated to lift or lower the cross-head 251 which motion is transmitted through the cables 255 to the trenching frame 161 and to the trenching wheel 162 (Figs. 1 and'3).

The control valve 263 is of a type well-known in the art for exercising control of a multiplicity of jacks from a single source of oil under pressure by the manipulation of a separate lever for controlling each of the jack means aforesaid. Thus manipulation of the lever 264 controls the power actuation of the jacks and manipulation of the lever 265 controls the power actuation of jack 249. Means exist in the valve 263 for feeding the oil into the various jacks so that the plungers thereof can be extended, locked in position, or drained, with the oil flowing back through the valve and into the reservoir 260. At the will of the operator, by the operation of valve 263, the pair of jacks 140 on the one hand and the jack 249 on the other can be operated in any manner described, up or down, or locked in any selected position, simultaneously or independently.

After pipe has been laid in a trench, the grader-trencher 29 may be employed as a simple bulldozer to fill the trench and level the ground thereover.

Where dirt must be loaded into a truck, this may be accomplished with the grader-trencher 29 by replacing the mold board 134 with a dump scoop bucket 280 as shown in Fig. 2. This bucket, however, is not considered as any part of the present invention.

Operation At the start of the operation of the grader and trencher 2! the counter-balancing and grading device 23 is elevated and the trenching attachment 22 is also elevated as shown in full lines in Fig. 1. These elements of the device are locked in that position by the correct manipulation of the hydraulic control handles 264 and 265. By virtue of the counter-balancing of the trenching attachment 22 by the grading device 23, bringing the center of gravity of the entire mass Well forward of the axis of the rear Wheel 25, the tractor 21 may be operated in the manner of an ordinary industrial tractor.

The motor 27 having been started, the tractor 21 is driven along the highway by the operator in the ordinary manner to the place where it is desired to effect a trenching operation. It is readily apparent that with the entire device 20 traveling on a pneumatic rubber tired chassis, the highway is undamaged and a minimum of damage is done to landscape surfaces over which the tractor 21 must move, after leaving the highway to reach its operating position. Having reached this position, the operator manipulates the gear-shift lever 116 to shift the gear 101 of the power takeoff 40 to provide a proper,

drive ratio between the shaft 43 and the trenching attac'hment shaft 178. This, of course, is done while the clutch of the motor 27 is disengaged. The operator at this time also manipulates the gear shift levers 119 V and the lever 58, to select the desired speed ratio at which the rear wheels 25 will be driven when the motor clutch is thrown in.

By manipulation of the valve lever 265 the operator now lowers the trenching attachment 22 by permitting the escape of oil from the lower end of jack 249 to the bleeder valve 268 and thence to the line 267, valve 263 and line 270 to the reservoir 260. As the trenching. wheel 162 approaches the ground in its descent, the clutch of' the motor is engaged to rotate the trenching wheel at a drive ratio determined by the location of the gear 101- in the power takeoff 40.

It the operator has set the gear trains in the original and secondary transmissions 33 and 39 to cause rotation 9 of shaft 42, when the motor clutch is engaged this will cause rotation of the wheels 25 when the clutch is thrown in to start rotation of the trenching wheel 162.

By the controls above described, the trenching wheel 162 is thus caused to descend into the ground and rotate in digging relation therewith, while the tractor 21 is caused to move forward, at any desired speed within the range permissible, so as to dig a trench of that depth to which the trenching wheel 162 is allowed to descend and at which, by manipulation of the valve lever 265, the operator checks the descent of the trenching wheel.

Fig. 1 clearly illustrates the relatively short wheel base of the tractor 21. Coupled with the fact that it is equipped with rubber tires, this gives a tremendous facility of maneuverability to the combination gradertrencher 10, the ability to travel over highways under its own power at speeds, up to thirty miles per hour plus the great advantage of being able to travel over lawns, walks, curbs and other features of residential and park grounds without seriously damaging these.

All these things are made possible and highly practical by the action of the counter-balancing grading device 23 being combined in the same structure with the tractor 21 and trenching attachment 22 and operated simultaneously and conjointly therewith.

While the grader-trencher 20 is merely travelling and neither grading, nor trenching, nor grading-trenching, both the trenching device 22 and the device 23 are elevated well out of contact with the ground as shown in full lines in Fig. 1. These conditions prevail While the grader-trencher is travelling under its own power between jobs and while it is being manipulated into position a the scene of each job, to start a trenching operation.

This position in most cases is with the entire gradertrencher 20 located in advance of the spot where the digging of the trench is to commence. The grader-trencher is of course aligned with and facing the line of the trench to be dug. The counter-balancer-grader 23 is now lowered to its broken line position shown in Fig. l and the tractor 21 started moving forward slowly causing the mold board 134 to shave the dirt away down to a smooth, grade-level surface onto which the tractor 21 proceeds to travel. Inasmuch as the trenching wheel 162 was thrown into gear before the tractor started forward, it has been rotating although suspended above the ground. Now, as the machine 20 arrives at the point where the ditch is to start, the lever 265 is manipulated to lower the wheel 162 into digging relation with the ground and it is allowed to continue down, as it digs its way, to the proper level for the bottom of the trench.

The forward movement of the tractor may be halted until the wheel 162 reaches the desired level of the trench bottom or the tractor may remain in forward motion thus forming a gradual inchne down to that level at the start of the ditch. The mold board 134 remains in lowered position however and thus determines, as the tractor advances, the level on which the tractor i supported, and assures the tractors being supported on a continuuous substantially plane ground surface throughout its travel in digging the trench.

The accuracy of the trenching attachment 22 in the formation of a trench is thus greatly enhanced and the attachment operates with much less wear and tear thereon than takes place when the trenching operation must be performed while the tractor 21 is travelling over ungraded ground.

The means provided in the present invention for guiding the trenching wheel frame 161 as the latter is lowered in the initiating of a trenching operation provides precise guides at different levels for said frame thus insuring that the trenching wheel 162 digs a trench accurately as it is lowered and while it is operating along a given path while lowered. The guide means referred to comprises, at its upper end, the rollers 177 and the cooperation of these with the arcuate channel guides 148. At a lower level, the

guide means for the trenching wheel frame 161.compris'es the two arms 185, their mounting on a common axis 152 at their front ends and their location in close proximity to and in bearing relation against the outer faces of the vertical channels 144 of the mast 143 and the corresponding outer faces of the arcuate channel guides 148 see Fig. 7).

The precise guiding of the trenching wheel frame 161 above referred to permits driving of the trenching wheel 162 from only one side to be entirely practical. This drive eliminates considerable expense hitherto believed essential in rotary trenchers.

I claim:

1. In a rotary wheel trench digging attachment for at'ractor having a motor, the combination of: a main frame adapted, when in use, to extend lengthwise of and be rigidly secured to said tractor; a guide tower provided on and extending upwardly from the rear end of said main frame, said tower including a pair of transversely spaced guide channels; a trenching wheel frame; a trenching wheel rotatably mounted on said trenching wheel frame; a driven shaft for driving said trenching wheel; means for rotatably mounting said driven shaft transversely on said trenching wheel frame; guide rollers provided on said trenching wheel frame on a common axis parallel with said driven shaft and spaced upwardly from said shaft a substantial distance, said rollers extending into and being guided by said channels to guide and determine the path of movement of the upper portion of said trenching wheel frame when the latter is shifted to lower and raise said trenching wheel; a pair of guide arms disposed outwardly alongside of and guided by said tower, the rear ends of said arms being pivotally connected with said trenching wheel frame on the axis of said driven shaft; means provided on said main frame for coaxially pivoting the forward ends of said arms on said main frame on a fixed axis relative to the latter, said arms, in swinging about said fixed axis, determining the path of movement of the axis of pivotal attachment of said arms with said trenching wheel frame when the latter is shifted to lower and raise said trenching wheel; power means actuated by said motor and extending to said coaxial pivoting means; drive means extending from said pivoting mean along one of said arms and transmitting power from said power means to said driven shaft to drive said trenching wheel; and means driven by said motor for lifting and lowering said trenching wheel frame along the path determined by said guide channels and said means for pivotally mounting the forward ends of said guide arms on said main frame.

2. A combination as in claim 1, in which said tower includes a primary pair of channels which are substantially straight and which face each other in spaced relation, and a secondary pair of channels which curve rearwardly and are secured at their upper and lower ends to said primary channels, said secondary channels receiving said rollers and thus guiding the upper portion of said trenching tool frame when the latter is lowered and raised, and in which said means for raising and lowering said trenching wheel frame comprises a cross-head which extends into and is vertically slidable in said primary channels, sheave means mounted on said cross-head, cable means secured to said main frame and extending upwardly over said sheave means and then downwardly to connect to said trenching wheel frame, and a hydraulic jack operating between said main frame and said cross-head and operable by liquid delivered under pressure thereto from the motor of said tractor, to raise and lower said crosshead.

3. In a rotary wheel trench digging attachment for a tractor having a motor, the combination of: a main frame adapted, when in use, to extend lengthwise of and be rigidly secured to said tractor; a guide tower provided on and extending upwardly from the rear end of said main frame, said tower including a pair of transversely spaced 1- guide channels; a trenching wheel frame; a trenching wheel rotatably mounted on said trenching wheel frame; a driven shaft for driving said trenching wheel; means for rotatably mounting said driven shaft transversely on said trenching wheel frame; guide rollers provided on said trenching wheel frame on a common axis parallel with said shaft, and spaced upwardly a substantial distance from said shaft, said rollers extending into, and being guided by said channels to guide and determine the path of movement of the upper portion of said trenching wheel frame when the latter is shifted to lower and raise said trenching wheel; a pair of guide arms disposed outwardly alongside and guided by said tower, the rear ends of said arms being pivotally connected with opposite sides of said trenching wheel frame on the axis of said driven shaft; means on said main frame to which the front ends of said arms are pivotally attached to permit vertical swinging of said arms alongside and guided by said tower, said arm mounting means determining the path of movement of the axis of pivotal attachment of said arms with said trenching tool frame when the latter is shifted to lower and raise said trenching wheel; power means actuated by said motor and extending to said coaxial pivoting means; drive means extending from said coaxial pivoting means along one of said arms and connecting said power means to said driven shaft to drive said trenching wheel; and means on said tower for lifting and lowering said trenching wheel frame along the path determined'by said guide channels and said guide arm mounting means.

' 4. In a trench digging attachment for a tractor having a motor, the combination of: a main frame adapted, when in use, to extend lengthwise of and be rigidly secured to said tractor; a guide tower provided on and extending upwardly from the rear end of said main frame, said tower including a pair of transversely spaced guide channels; a trenching tool frame; a trenching tool mounted on said trenching tool frame, said tool having'an endless series of continuously travelling digging buckets; a driven shaft for driving said trenching tool; means for rotatably mounting said driven shaft transversely on said trenching tool frame; guide rollers provided on said trenching tool frame on a common axis parallel with said driven shaft and spaced upwardly from said shaft a substantial distance, said rollers extending into and being guided by said channels to guide and determine the path of movement of the upper portion of said trenching tool frame when the latter is shifted to lower and raise said trenching tool; a pair of guide arms disposed outwardly alongside of and guided by said tower, the rear ends of said arms being pivotally connected with said trenching tool frame on the axis of said driven shaft; means provided on said main frame for coaxially pivoting the forward ends of said arms on said main frame, said arms, in swinging about their forward ends, determining the path of movement of the axis of pivotal attachment of the rear ends of said arms with said trenching tool frame when the latter is shifted to lower and raise said trenching tool; power means actuated by said motor and extending to said coaxial pivoting means; drive means extending along one of said arms and transmitting power from said power means to said driven shaft to drive said trenching tool; and means driven by said motor for lifting and lowering said trenching tool frame along the path determined by said guide channels and by the pivoting of said guide arms on said main frame.

5. A combination, as in claim 4, in which the uppermost portions of said guide channels are turned sharply forwardly to produce a substantial forward rotation of said trenching tool frame about the axis of said driven shaft during the final portion of the upward travel of said trenching tool frame.

References Cited in the file of this patent UNITED STATES PATENTS 561,939 Hetlesaeter June 9, 1896 1,108,268 Stahl Aug. 25, 1914 1,476,375 Shook Dec. 4, 1923 1,831,324 Seward Nov. 10, 1931 1,957,221 McCray May 1, 1934 2,140,105 Cluster Dec. 13, 1938 2,165,299 Penote July 11, 1939 2,169,184 French Aug. 8, 1939 2,233,237 Anderson et al Feb. 25, 1941 2,252,837 Dicke Aug.19, 1941 2,276,000 Stumpf Mar. 10, 1942 2,302,509 Tangen Nov. 17, 1942 2,321,352 Askue June 8, 1943 2,423,132 Vaughn July 1, 1947 2,425,746 Lichtenberg Aug. 19, 1947 2,426,410 Owen Aug. 26, 1947 2,488,990 South Nov. 22, 1949 2,519,075 Schmidt Aug. 15, 1950 2,531,818 Kranick .Nov. 28,1950 2,598,339 Askue May 27, 1952 2,617,314 Everett Nov. 11, 1952 

